From ``The Cat Who Walks Through Walls'', by Robert A. Heinlein.

Published by G.P. Putnam's Sons, New York, 1985.

I was in the pilot's couch; Gwen had the copilot's position on my right. I looked toward her and then realized that I was still wearing that silly eyepatch. No, delete ``silly'' -- it had, quite possibly, saved my life. I took it off, stuffed it into a pocket. Then I took it off, stuffed it into a pocket. Then I took that fez off, looked around for somewhere to put it -- tucked it under my chest belt. ``Let's see if we are secure for space,'' I said.

``Isn't it a little late for that, Richard?''

``I always do my check-off lists after I lift,'' I told her. ``I'm the optimistic type. You have a purse and a large package from Macy's; how are they secured?''

``They are not, as yet. If you will refrain from goosing this craft while I do it, I'll unstrap and net them.'' She started to unstrap.

``Whoops! Before unstrapping you must get permission from the pilot.''

``I thought I had it.''

``You do now. But don't make that mistake again. Mr. Christian, His Majesty's Ship Bounty is a taut ship and will remain that way. Bill! How are you doing back there?''

``M okay.''

``Are you secure in all ways? When I twist her tail, I don't want any loose change flying around the cabin.''

``He's belted in properly,'' Gwen assured me. ``I checked him. He is holding Tree-San's pot flat against his tummy and he has my promise that, if he lets go of it, we will bury him without rites.''

``I'm not sure it will stand up under acceleration.''

``Neither am I but there was no way to pack it. At least it will be in the correct attitude for acceleration -- and I'm reciting some spells. Dear man, what can I do with this wig. It's the one Naomi uses for public performances; it's valuable. It was sweet indeed of her to insist that I wear it -- it was the final, convincing touch, I think -- but I don't see how to protect it. It's at least as sensitive to acceleration as Tree-San.''

``Durned if I know -- and that's my official opinion. But I doubt that I need to push this go-buggy higher than two gee.'' I thought about it. ``How about the glove compartment? Take all of the Kleenex out of the dispenser and crumple it up around the wig. And some inside it. Will that work?''

``I think so. Time enough?''

``Plenty of time. I made a quick estimate at Mr. Dockweiler's office. In order to land at Hong Kong Luna port and in sunlight I should start moving into a lower orbit about twenty-one hundred. Loads of time. So go ahead, do whatever you need to do ... while I tell the computer pilot what I want to do. Gwen, can you read all the instruments from your side?''

``Yes, sir.''

``Okay, that's your job, that and the starboard viewport. I'll stick to power, attitude, and this baby computer. By the way, you're licensed, aren't you?''

``No point in asking me now, is there? But let not your heart be troubled, dear; I was herding sky junk before I was out of high school.''

``Good.'' I did not ask to see her license -- as she had pointed out, it was too late to matter.

And I had noticed that she had not answered my question.

(If ballistics bores you, here is another place to skip.)

A daisy-clipping orbit of Luna (assuming that Luna has daisies, which seems unlikely) takes an hour and forty-eight minutes and some seconds. Golden Rule, being three hundred kilometers higher than a tall daisy, has to go farther than the circumference of Luna (10,919 kilometers), namely 12, 805 kilometers. Almost two thousand kilometers farther -- so it has to go faster. Right?

Wrong. (I cheated.)

The most cock-eyed, contrary to all common sense, difficult aspect of ballistics around a planet is this: To speed up, you slow down; to slow down, you speed up.

I'm sorry. That's the way it is.

We were in the same orbit as Golden Rule, three hundred klicks above Luna, and floating along with the habitat at one and a half kilometers per second (1.54477 k/s is what I punched into the pilot computer ... because that was what it said on the crib sheet I got in Dockweiler's office). In order to get down to the surface I had to get into a lower (and faster) orbit ... and the way to do that was to slow down.

But it was more complex than that. An airless landing requires that you get down to the lowest (and fastest) orbit ... but you have to kill that speed so that you arrive at contact with the ground at zero relative speed -- you must keep bending it down so that contact is straight down and without a bump (or not much) and without a skid (or not much) -- what they call a ``synergistic'' orbit (hard to spell and even harder to calculate).

But it can be done. Armstrong and Aldrin did it right the first time. (No second chances!) But despite all their careful mathematics it turned out there was one hell of a big rock in their way. Sheer virtuosity and a hatful of fuel bought them a landing they could walk away from. (If they had not had that hatful of fuel left, would space travel have been delayed half a century or so? We don't honor our pioneers enough.)

There is another way to land. Stop dead right over the spot where you want to touch down. Fall like a rock. Brake with your jet so precisely that you kiss the ground like a juggler catching an egg on a plate.

One minor difficulty -- Right-angled turns are about the most no-good piloting one can do. You waste delta vee something scandalous -- your boat probably doesn't carry that much fuel. (``Delta vee'' -- pilot's jargon for ``change in velocity'' because, in equations, Greek letter delta means a fractional change and ``v'' stands for velocity -- and please remember that ``velocity'' is a direction as well as a speed, which is why rocket ships don't make U-turns.)

I set about programming into the Volvo's little pilot computer the sort of synergistic landing Armstrong and Aldrin made but one not nearly as sophisticated. Mostly I had to ask the piloting computer to call up from its read-only memory its generalized program for landing from an orbit circum Luna ... and it docilely admitted that it knew how ... and then I had to inject data for this particular landing, using the crib sheet supplied by Budget Jets.

Finished with that, I told the computer pilot to check what I had entered; it reluctantly conceded that it had all it needed to land at Hong Kong Luna at twenty-two hundred hours seventeen minutes forty-eight point three seconds.

Its clock read 1957. Just twenty hours ago a stranger calling himself ``Enrico Schultz'' had sat down uninvited at my table in Rainbow's End -- and five minutes later he was shot. Since then, Gwen and I had wed, been evicted, ``adopted'' a useless dependent, been charged with murder, and run for our lives. A busy day! -- and not yet over.

I had been living in humdrum safety much too long. Nothing gives life more zest than running for your life. ``Copilot.''

``Copilot aye aye!''

``This is fun! Thank you for marrying me.''

``Roger, Captain darling! Me, too!''

This was my lucky day, no doubt about it! A lucky break in the timing had kept us alive. At this instant Chief Franco must be checking every passenger entering the twenty o'clock shuttle, waiting for Dr. Ames and Mistress Novak to claim their reservations -- while we were already out the side door. But, while that critical timing saved our lives, Lady Luck was still handing out door prizes.

How? From Golden Rule's orbit our easiest landing on Luna would involve putting down at some point on the terminator -- least fuel consumed, smallest delta vee. Why? Because we were already on that terminator line, going pole to pole, south to north, north to south, so our simplest landing was to bend it down where we were, never change our heading.

To land in the east-west direction would involve throwing away our present motion, then expending still more delta vee making that foolish right-angle turn -- then programming for landing. Maybe your bank account can afford this waste; your skycar cannot -- you're going to find yourself sitting up there with no fuel and nothing under you but vacuum and rocks. Unappetizing.

To save our necks I was happy to accept any landing field on Luna ... but that door prize from Lady Luck included landing at my preferred field (Hong Kong Luna) just about daybreak there, with only an hour spent parked in orbit waiting for the time to tell the computer pilot to take us down. What more could I ask for?

At that moment we were floating over the backside of the Moon -- as corrugated as the backside of an alligator. Amateur pilots do not land on the far side of Luna for two reasons: 1) mountains -- the side of the Moon turned away from Earth makes the Alps look like Kansas; 2) settlements -- there aren't any to speak of. And let's not speak of settlements that aren't to speak of, because it might make some unspeakable settlers quite angry.

In another forty minutes we would be over Hong Kong Luna just as sunrise was reaching it. Before that time I would ask for clearance to land and for ground control on the last and touchiest part of the landing -- then spend the next two hours in going around behind again and gently lowering the Volvo down for landing. Then it would be time to turn control over to Hong Kong Luna ground control but, I promised myself, I would stay on overrides and work the landing myself, just for drill. How long had it been since I had shot an airless landing myself? Callisto, was it? What year was that? Too long!

At 2012 we passed over Luna's north pole and were treated to earthrise ... a breathtaking sight no matter how many times one has seen it. Mother Earth was in half phase (since we were ourselves on Luna's terminator) with the lighted half to our left. It being only days past summer solstice, the north polar cap was tilted into full sunlight, dazzling bright. But North America was almost as bright, being heavily cloud-covered except part of the Mexican west coast.

I found that I was holding my breath, and Gwen was squeezing my hand. I almost forgot to call HKL ground control.


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11.08.01 / Garth Huber